(1) Field of the Invention
The present invention relates to a treating liquid supplying apparatus for a substrate spin treating apparatus for supplying photoresist or other surface treating liquids to substrates, such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays or substrates for optical disks, to effect a surface treatment thereof. Specifically, such a treating liquid supplying apparatus has a plurality of nozzles for supplying the treating liquids to a substrate supported for a spinning motion, a plurality of tubes for connecting the nozzles to treating liquid storages, temperature control piping for contacting the tubes to maintain the treating liquids therein at a constant temperature, and a nozzle moving device for moving a selected one of the nozzles to a dispensing position above the substrate under treatment.
(2) Description of the Related Art
With this type of spin treating apparatus, it is desired that a plurality of treating liquid supplying systems be provided for one such apparatus in order selectively to supply plural types of treating liquids having different components or different degrees of viscosity. For this purpose, a known apparatus, as disclosed in Japanese Utility Model Publication No. 4-52990, for example, includes a transfer arm for gripping and moving a selected one of a plurality of nozzles arranged in a standby position to a dispensing position above a substrate.
The known apparatus, however, has the following drawbacks:
(1) When the transfer arm grips and moves one of the nozzles, the hardness of a tube connected to this nozzle imparts a resistance to vary a nozzle posture. Such a resistance places the nozzle in an unsteady dispensing posture upon arrival at the dispensing position above the substrate, e.g. displaced from the predetermined dispensing position, or tilted instead of facing directly downward. As a result, the nozzle applies the treating liquid to inappropriate regions of the substrate. Generally, precision in the order of 0.1 mm is required for positions of the substrate to which the treating liquid is applied, in order to effect a uniform treatment. Such misapplication of the treating liquid results in a low quality treatment.
(2) The tube connecting each nozzle to its treating liquid source is displaced to a large extent when the nozzle is moved between standby position and dispensing position. Consequently, where the treating liquid supplying tube extends through temperature control piping for maintaining the treating liquid at a constant temperature, it is difficult to make a piping arrangement because of the rigidity of such a multiple pipe structure.
Conversely, where such temperature control piping is formed of a thin, flexible material to give priority to the piping arrangement, a temperature controlling fluid may flow through the pipes only in an insufficient quantity. Then, the treating liquid supplying tubes cannot receive a uniform temperature control peripherally thereof, which results in a reduced precision of temperature control.
(3) The tube is subjected to a considerable bending and twisting deformation, resulting in volume variations within the pipe. With such volume variations, the treating liquid tends to fall in large drops from the nozzle to the substrate.